Magnetic sensor device and method for producing same

ABSTRACT

A magnetic sensor device includes: a magnetic circuit for forming a magnetic field, a magnetoresistance effect element, and a heat dissipator. The magnetoresistance effect element outputs changes in the magnetic field as changes in a resistance value, and is arranged on a surface (of a +Z side) of the magnetic circuit at a conveyance path side thereof. The heat dissipator is arranged in close contact with the magnetic circuit at the opposite side thereof (−Z side) from the conveyance path.

TECHNICAL FIELD

The present disclosure relates to a magnetic sensor device and a methodfor producing the same.

BACKGROUND ART

Patent Literature 1 discloses a magnetic sensor device that is equippedwith a magnet and a magnetoresistance effect element for detection of anobject to be detected that is conveyed through a conveyance path. Amagnetic pole is disposed at one surface side of the magnet where theobject to be detected is conveyed, and the magnet generates anintersection magnetic field that intersects the object to be detected.The magnetoresistance effect element is arranged between the magnet andthe object to be detected. The magnetoresistance effect element has anoutput terminal and outputs as a change of resistance value a change ofa conveyance direction component of the intersection magnetic field dueto a magnetic component of the object to be detected conveyed throughthe intersection magnetic field. Further, Patent Literature 1 discloses,as a configuration of a magnetic circuit for generation of theintersection magnetic field, a configuration that disposes the object tobe detected between opposing magnets, and a configuration that disposesa magnet at one surface of the object to be detected and disposes amagnetic body opposing another surface of the object to be detected.

Patent Literature 2 mentions a magnetic sensor that is characterized inthat the magnetic sensor is equipped with a magnetoresistance element, aconductor layer and a resistance. The magnetoresistance element has anelement board and pairs of magnetosensitive parts arranged parallel toone another at a fixed spacing on the element board. The conductor layeris disposed at a position equidistance with each of pairs of themagnetosensitive part. The resistance is connected electrically inseries with the conductor layer.

CITATION LIST Patent Literature

-   Patent Literature 1: Unexamined Japanese Patent Application Kokai    Publication No. 2012-255770-   Patent Literature 2: Unexamined Japanese Patent Application Kokai    Publication No. H08-201493

SUMMARY OF INVENTION Technical Problem

In a magnetic sensor device, the component that emits the most heat inthe magnetic sensor device is the magnetoresistance effect element. Theresolution and number of magnetoresistance effect elements are low inconventional magnetic sensor devices such as those in Patent Literature1 and Patent Literature 2. Thus the amount of heat generation is low,and consideration of heat dissipation is not required in theconstruction of such conventional magnetic sensor devices. However, alarge number of magnetoresistance effect elements are arranged in orderto make a magnetic sensor device that has high resolution. Thus a largeamount of heat is generated, and the magnetic sensor device tends tobecome hot. The magnet used in the magnetic sensor device demagnetizeswhen the magnetic sensor device becomes hot, and thus the performance ofthe magnetic sensor device is likely to decline.

The object of the present disclosure is to solve the aforementioned typeof problem and to obtain a magnetic sensor device, and production methodthereof, that has excellent heat dissipation and is capable ofsuppressing the lowering of performance that is caused by heatgeneration by the magnetoresistance effect elements.

Solution to Problem

In order to achieve the aforementioned object, the magnetic sensordevice of the present disclosure is equipped with a magnetic circuit forforming a magnetic field, magnetoresistance effect elements and a heatdissipator. The magnetoresistance effect elements output a change ofmagnetic field as a change of resistance value, and are arranged on asurface on an object-to-be-detected conveyance path side of the magneticcircuit. The heat dissipator is arranged in close contact with themagnetic circuit at a surface other than the conveyance path sidesurface of the heat dissipator.

Advantageous Effects of Invention

According to the present disclosure, the heat dissipator is arranged inclose contact with the heat dissipator at a surface of the magneticcircuit other than that of the conveyance path side. Thus heat increaseof the magnetic sensor device is suppressed, which enables suppressionof the demagnetization of the magnet by heat. This has the effect ofenabling the obtaining of the magnetic sensor device, and a productionmethod thereof, that are capable of suppressing lowering of performanceof the magnetoresistance effect elements.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional drawing of a magnetic sensor device ofEmbodiment 1 of this disclosure;

FIG. 2A is a perspective view of the magnetic sensor device ofEmbodiment 1, with a cover side oriented upward;

FIG. 2B is a perspective view of the magnetic sensor device ofEmbodiment 1, with a signal processing board side oriented upward;

FIG. 2C is a cross-sectional drawing of a case of Embodiment 1;

FIG. 3A is a perspective view of a metallic carrier in the magneticsensor device of Embodiment 1;

FIG. 3B is a cross-sectional drawing of the metallic carrier in themagnetic sensor device of Embodiment 1;

FIG. 4A is a perspective view illustrating a state of assembly of asensor board, carrier, magnetoresistance effect elements and signalamplification ICs in the magnetic sensor device of Embodiment 1;

FIG. 4B is a perspective view illustrating a state of assembly of thesensor board, carrier, magnetoresistance effect element and signalamplification IC in the magnetic sensor device of Embodiment 1;

FIG. 4C is a plan view of the sensor board of the magnetic sensor deviceof Embodiment 1;

FIG. 5 is a perspective view illustrating a state of contact between apermanent magnet and a yoke in the magnetic sensor device of Embodiment1;

FIG. 6 is a cross-sectional drawing illustrating the state in which thecarrier and a permanent magnet are attached and integrated together inthe state of FIG. 4 of the magnetic sensor device of Embodiment 1;

FIG. 7 is a cross-sectional drawing illustrating a state of attachmentof components of the FIG. 6 state to the case in the magnetic sensordevice of Embodiment 1;

FIG. 8 is a cross-sectional drawing illustrating a state of attachmentof the heat dissipator in the state of FIG. 7 for the magnetic sensordevice of Embodiment 1;

FIG. 9 is a cross-sectional drawing illustrating a state of attachmentof the cover in the state of FIG. 8 for the magnetic sensor device ofEmbodiment 1;

FIG. 10 is a cross-sectional drawing of the case in the magnetic sensordevice of Embodiment 1;

FIG. 11 is a cross-sectional drawing of a magnetic sensor device of acomparative example;

FIG. 12 is a cross-sectional drawing of a magnetic sensor device ofEmbodiment 2 of this disclosure;

FIG. 13A is a perspective view illustrating in partial cross section ofthe case of a magnetic sensor device of Embodiment 3 of this disclosure;

FIG. 13B is a cross-sectional drawing of the case of the magnetic sensordevice of Embodiment 3;

FIG. 14 is a cross-sectional drawing of the magnetic sensor device ofEmbodiment 3;

FIG. 15 is a perspective view of a case of a magnetic sensor device ofEmbodiment 4 of this disclosure;

FIG. 16 is a cross-sectional drawing of the magnetic sensor device ofEmbodiment 4;

FIG. 17 is a perspective view of a heat dissipator in a magnetic sensordevice of Embodiment 5 of this disclosure;

FIG. 18 is a cross-sectional drawing of the magnetic sensor device ofEmbodiment 5;

FIG. 19 is a perspective view of the heat dissipator of a magneticsensor device of Embodiment 6 of this disclosure;

FIG. 20 is a cross-sectional drawing of the magnetic sensor device ofEmbodiment 6; and

FIG. 21 is a cross-sectional drawing of a magnetic sensor device ofEmbodiment 7 of this disclosure.

DESCRIPTION OF EMBODIMENTS Embodiment 1

A magnetic sensor device, and a production method thereof, of Embodiment1 of this disclosure are described below. Furthermore, in all theembodiments, the expression “conveyance of the object to be detected”,in addition to the case of conveyance of the object to be detected, istaken to further include the case of moving the magnetic sensor devicein the conveyance direction (Y direction of FIG. 1) without moving theobject to be detected. Furthermore, the X direction is termed the“reading-width direction”.

Further, the three axes labeled X, Y and Z in the drawings are threeorthogonal axes. The X axis indicates the reading-width direction(longitudinal direction of the magnetic sensor device) of the magneticsensor device. The Y axis indicates the conveyance direction (conveyancedirection of the conveyed object to be detected, transverse direction ofthe magnetic sensor device) of the magnetic sensor device. The Z axisindicates the height direction of the magnetic sensor device. Further,the locations of conveyance of the object to be detected in theconveyance direction are termed the “conveyance path of the object to bedetected”. Here, the origin of the X axis is the center of X-axisdirection length of the magnetic sensor device, and the direction of thearrow within the figures is the + direction (positive direction). Theorigin of the Y axis is the center of Y-axis direction length of themagnetic sensor device, and the direction of the arrow within thefigures is the + direction (positive direction). The origin of the Zaxis is the center of Z-axis direction length of the magnetic sensordevice, and the direction of the arrow within the figures is the +direction (positive direction). Within the figures, identical referencesigns indicate the same or equivalent components.

FIG. 1 is a cross-sectional drawing at the Z-Y plane of the magneticsensor device of Embodiment 1 of this disclosure. The magnetic sensordevice 100 illustrated in FIG. 1, for example, is used in a magneticcard reader or in an identification apparatus for printed articles (suchas paper currency and the like) printed using magnetic ink. The magneticsensor device 100, along the Z direction perpendicular to the conveyancedirection 21 (Y direction) of the object to be detected 20 such as papercurrency and the like, is equipped with a magnetic circuit 30 and a heatdissipator 11. The magnetic circuit 30 is equipped with a magnet 9, ayoke 10 and a metallic carrier 7 carrying magnetoresistance effectelements 4, having a magnetic carrier 7 a, and a non-magnetic carrier 7b. The magnet 9 and the magnetic carrier 7 a constituting the magneticcircuit 30 form a magnetic field by magnetic flux from one pole of themagnet 9 passing through the magnetic carrier 7 a, overflowing to aspace at the conveyance path side, turning back, passing through theyoke 10, and returning to the other pole of the magnet 9. The object tobe detected 20 is conveyed through the conveyance path in a manner so asto pass through the void (space) where the magnetic field is formed.

Further, the magnetic sensor device 100 is equipped with a cover 1, acase 2, a sensor board 3, a signal amplification integrated circuit(referred to throughout the present disclosure as “IC”) 5, a wire 6, afastener 8 and a signal processing board 13.

Although the conveyance direction 21 in FIG. 1 is the +Y direction, the−Y direction may also be used.

FIG. 2A and FIG. 2B are perspective views of the magnetic sensor deviceof Embodiment 1 of this disclosure. FIG. 2A is a perspective view withthe cover 1 oriented upward. FIG. 2B is a perspective view with thesignal processing board 13 oriented upward. As illustrated in FIGS. 2Aand 2B, the cover 1 is a component constituting theobject-to-be-examined conveyance surface of the magnetic sensor device100. The cover 1 extends in the X direction. The cover 1 is arranged atthe conveyance path side of the case 2. The cover 1 has a conveyancesurface 1 b, which extends along the conveyance path, and tapers 1 a.The tapers 1 a are tilted toward a direction opposite to the conveyancepath side, and are continuous with an upper and a lower end of theconveyance surface 1 b in the conveyance direction 21. The cover 1 isshaped so as to cover the magnetoresistance effect elements 4.

The case 2 is formed from a housing as illustrated in FIG. 1. Holes 2 band 2 c for containing and holding the various components constitutingthe magnetic sensor device 100, holes for positioning, and a boardmounting surface 2 f are formed in the case 2.

The sensor board 3 is arranged between the cover 1 and a metalliccarrier 7. The sensor board 3 has a structure that laminates in the Zdirection a non-conductive member 3 a and a conductive member 3 b, whichforms a wiring pattern. The non-conductive member 3 a is fixed bydouble-sided tape, adhesive and the like to the cover 1. The conductivemember 3 b is fixed by double-sided tape, adhesive and the like to themetallic carrier 7.

The magnetoresistance effect element 4 is arranged at the conveyancepath side (+Z side) of the magnet 9. Further, the magnetoresistanceeffect element 4 is fixed by adhesive and the like to the +Z side(conveyance path side) surface of the magnetic carrier 7 a. Themagnetoresistance effect element 4 is electrically connected through thewire 6 to the conductive member 3 b of the sensor board 3.

The signal amplification IC 5 is fixed by adhesive and the like to a +Zside (conveyance path side) surface of the non-magnetic carrier 7 b. Thesignal amplification IC 5 is electrically connected through the wire 6to the conductive member 3 b of the sensor board 3. By this means, thesignal amplification IC 5 is electrically connected to themagnetoresistance effect elements 4.

FIG. 3A is a perspective view of the metallic carrier, and FIG. 3B is across-sectional drawing of the metallic carrier. As illustrated in FIGS.3A and 3B, the metallic carrier 7 is in close contact with theconveyance path side surface of the magnet 9 (+Z side surface of themagnet 9) and carries the magnetoresistance effect element 4. Themetallic carrier 7 is integrally formed by contact between the magneticcarrier 7 a and the non-magnetic carrier 7 b in the Y direction(conveyance direction 21). The metallic carrier 7 is fitted from a hole2 b opening (conveyance path side opening) of the case 2, and is fixedusing adhesive and the like.

The magnet 9, as illustrated in FIG. 1, is constituted by a permanentmagnet. The magnet 9 is fixed by adhesive and the like to a surface ofthe metallic carrier 7 of the side thereof opposite to the surfacecontacting the sensor board 3 (fixed to the −Z side surface of themetallic carrier 7).

The yoke 10 is close attached to a surface of the side opposite to thesurface (−Z side surface of the magnet 9) of the magnet 9 closelyattached to the metallic carrier 7. The yoke 10 is fixed by adhesive andthe like to the surface (−Z side surface of the magnet 9) of the magnet9 opposite to the surface contacting the metallic carrier 7. The yoke 10is a plate of a magnetic metal.

The heat dissipator 11 is in close contact with a surface (−Z sidesurface of the yoke 10) of the yoke 10 that is opposite to the surfaceof close contact with the magnet 9. This heat dissipator 11 is acomponent for release of internal heat of the magnetic sensor device 100to the external air. The heat dissipator 11 is fitted into a hole 2 eopening (opening of the side opposite to the conveyance path side) ofthe case 2, and is fixed using adhesive and the like to the surface (−Zside surface of the yoke 10) of the yoke 10 of the side opposite to thesurface contacting the magnet 9. The heat dissipator 11 has fins 11 bprojecting at the side thereof opposite to the conveyance path side. Thefins 11 b are arranged in rows in the Y direction and are integrallyformed with the main body of the heat dissipator 11.

That is to say, the heat dissipator 11 is in close contact with thesurface of the magnetic circuit 30 opposite to the conveyance path side,which is a surface other than the conveyance path side surface of themagnetic circuit 30.

The signal processing board 13 is electrically connected through a cable3 c to the sensor board 3. The signal processing board 13 is attached tothe side (−Z side of the case 2) of the case 2 opposite to the sidecontacting the cover 1. The signal processing board 13 covers the heatdissipator 11 by this means.

As illustrated in FIGS. 2A and 2B, the cover 1 is a component comprisingthe object-to-be-examined conveyance surface of the magnetic sensordevice 100. The cover 1 is produced by bending a thin metal sheet. Thecover 1 has tapers 1 a from the conveyance path side of the object to bedetected 20 tilted toward the direction (−Z direction) opposite to thisconveyance path side. The tapers 1 a function as conveyance guides.During conveyance, due to these tapers 1 a, the object to be detected 20moves along the tapers 1 a. This configuration enables prevention of theobject to be detected 20 from moving in a direction other than theconveyance direction (Y direction).

The cover 1 has a role of protecting the magnetic sensor device 100 fromshock and wear due to collision, chafing and the like during conveyanceof the object to be detected 20 upon the magnetic sensor device 100.Further, noise generation occurs in the signal amplification IC 5 inreaction to light, and thus the cover 1 has a role of blocking externallight so that the external light does not reach the signal amplificationIC 5. This cover 1 is arranged between the object to be detected 20 andthe magnetoresistance effect elements 4. Thus the material of the cover1 is preferably non-magnetic in order not to influencemagneto-sensitivity of the magnetic sensor device 100.

In Embodiment 1 of this disclosure, the cover 1 is produced by bending athin metal sheet. However, the aforementioned material and productionmethod are not limiting. As long as the cover 1 has the aforementionedroles, the cover 1 may be produced by a method other than thin metalsheet bending.

FIG. 2C is a cross-sectional drawing of the case of the magnetic sensordevice. As illustrated in FIGS. 2A to 2C, the case 2 is a component forinternal containment of other components. The case 2 is formed from ablack resin. The step 2 a, the holes 2 b, 2 c and 2 e, the boardmounting surface 2 f, and the board mounting hole 2 g are formed in thecase 2.

The step 2 a is used for Z-direction support of the metallic carrier 7assembled together with the sensor board 3, magnetoresistance effectelements 4, signal amplification IC 5 and wire 6. The step 2 a isarranged at the conveyance path side of the case 2.

The hole 2 b has an opening end in the +Z side surface and is used forX-Y direction positioning of the metallic carrier 7 integrated togetherwith the sensor board 3, magnetoresistance effect element 4, signalamplification IC 5 and wire 6. The hole 2 b is arranged in theconveyance path side (+Z side) of the case 2, and the step 2 a is usedas a bottom portion of the hole 2 b.

The hole 2 c is used for arrangement and X-Y direction positioning ofthe integrated magnet 9 and yoke 10. The hole 2 c is a through hole thatpenetrates from the hole 2 b to the hole 2 e.

The hole 2 e has an opening formed in the −Z side surface, and is usedfor X-Y direction positioning of the heat dissipator 11 duringattachment of the heat dissipator 11 to the yoke 10. The hole 2 e isarranged at the surface of the case 2 of the side (−Z side) opposite tothe conveyance path side.

The board mounting surface 2 f is arranged at the surface of the side(−Z side) opposite to the side of the conveyance path of the object tobe detected 20. The board mounting surface 2 f is used for attachment ofthe signal processing board 13.

The board mounting hole 2 g is used for positioning of the signalprocessing board 13 and for fixing thereof to the case 2.

Noise generation occurs in the signal amplification IC 5 in reaction tolight, and thus the case 2 has a role of blocking external light so thatthe external light does not reach the signal amplification IC 5.

In Embodiment 1 of this disclosure, the case 2 is formed from the blackresin. However, use of the above material is not limiting. As long asthe case 2 has the aforementioned role, formation is possible using amaterial other than the black resin.

As illustrated in FIG. 1, the sensor board 3 has the non-conductivemember 3 a and the conductive member 3 b. The non-conductive member 3 ais used for arranging a space such that the cover 1 does not contact themagnetoresistance effect element 4, signal amplification IC 5, and wire6. Wiring for transmitting electrical signals of the magnetoresistanceeffect element 4 and the signal amplification IC 5 is arranged in theconductive member 3 b. The cable 3 c is used for transmission ofelectrical signals from the sensor board 3 to the signal processingboard 13.

The sensor board 3 is attached to the surface of the +Z side (side ofthe conveyance path of the object to be detected 20) of the metalliccarrier 7. The sensor board 3 is positioned by contact with the metalliccarrier 7. As shown in FIGS. 4A and 4B, positioning holes 3 d are formedin the sensor board 3. The positioning holes 3 d are formed in thevicinities of both X-direction end portions of the sensor board 3. Asillustrated in FIGS. 3A and 3B, positioning holes 7 c are formed in themetallic carrier 7. The positioning holes 7 c are formed in thevicinities of both X-direction end portions of the metallic carrier 7.As illustrated in FIGS. 3A, 3B, 4A and 4B, pins are inserted in thepositioning holes 3 d and 7 c. By this means, the positioning holes 3 dand 7 c are coaxially stacked, and thus the sensor board 3 is positionedrelative to the metallic carrier 7. The positioning holes 3 d and thepositioning holes 7 c are each formed in at least two locations.

As illustrated in FIG. 1, the magnetoresistance effect element 4 isfixed by adhesive and the like to the same surface of the magneticcarrier 7 a as that used for attachment of the sensor board 3.Z-direction position of the magnetoresistance effect element 4 isdetermined by contact with the magnetic carrier 7 a. Moreover, themagnetoresistance effect element 4 is arranged within the opening 3 eused for the magnetoresistance effect element 4 of the sensor board 3.As illustrated in FIG. 4C, the magnetoresistance effect element 4 isarranged on a virtual line L2 parallel to a straight line L1interconnecting the positioning holes 3 d at both ends of the sensorboard 3. However, the Y-direction position for fixing themagnetoresistance effect elements 4 is not limited to that of thisconfiguration. In response to the position of the object to be detected20, the virtual line L2 may be offset parallel to both the X directionand Y direction.

The magnetoresistance effect element 4 detects the change of theconveyance direction component of the magnetic field that occurs due toconveyance in the conveyance direction 21 of the object to be detected20, such as paper currency and the like, which includes a magneticcomponent. Specifically, the resistance value of the magnetoresistanceeffect element 4 changes with the change of the magnetic field. Based onthis change of the resistance value, the magnetoresistance effectelement 4 detects the change of the magnetic field. Then themagnetoresistance effect element 4 outputs a signal corresponding to theamount of change of the magnetic field.

As illustrated in FIG. 1, the signal amplification IC 5 is fixed byadhesive and the like to a surface of the non-magnetic carrier 7 b thatis the same as the surface of attachment of the sensor board 3.Z-direction position of the signal amplification IC 5 is determined bycontact with the non-magnetic carrier 7 b. Further, the signalamplification IC 5 is positioned in the X-Y plane of the signalamplification IC 5 by arrangement in the vicinity of the X-Y planecenter of the opening 3 f used for the signal amplification IC 5.

The signal amplification IC 5 amplifies the signal output from themagnetoresistance effect element 4.

The wire 6 electrically connects together the magnetoresistance effectelement 4 and the signal amplification IC 5 to the conductive member 3 bof the sensor board 3.

The metallic carrier 7 has the magnetic carrier 7 a and the non-magneticcarrier 7 b. Z-direction position of the metallic carrier 7 isdetermined by causing one Z-direction surface of the metallic carrier 7(surface of the side opposite to the conveyance path of the object to bedetected 20, −Z side surface) to contact the step 2 a of the case 2.

The metallic carrier 7 supports the sensor board 3 in the Z direction.The magnetic carrier 7 a has a role of directing the magnetic field ofthe magnet 9 in the Z direction.

One surface in the Z direction (−Z side surface, surface opposite to theside of the conveyance path of the object to be detected 20) of themagnet 9 contacts the yoke 10. The X-direction sizes of the magnet 9 andyoke 10 are equal, and the Y-direction sizes are also equal. Theintegrated magnet 9 and yoke 10 are arranged parallel to themagnetoresistance effect element 4. The surface (conveyance path sidesurface of the magnet 9) of the magnet 9 opposite to the surface ofcontact between the magnet 9 and the yoke 10 and the surface (surface ofthe metallic carrier 7 at the side opposite to the conveyance path side)of the metallic carrier 7 opposite to the surface of contact of thesensor board 3 of the metallic carrier 7 are fixed by adhesion.Z-direction position of the magnet 9 is determined by securing togetherthis surface of the magnet 9 and the surface of the metallic carrier 7.Further, the position of the magnet 9 in the X-Y plane relative to themagnetoresistance effect elements 4 is also determined. The magneticforces imparted to the magnetoresistance effect elements 4 and theobject to be detected 20 change when the Y-direction position of themagnet 9 changes, and thus the Y-direction position of the magnet 9 ispreferably finely adjusted according to the performance of the magneticsensor device 100.

The magnet 9 has a role of generating the magnetic field and impartingmagnetic force to the object to be detected 20. The yoke 10 has a roleof strengthening the magnetic field generated by the magnet 9.

The heat dissipator 11 is fixed by adhesive and the like to the surfaceof the yoke 10 opposite to the surface contacting the magnet 9. TheZ-direction position of the heat dissipator 11 is determined by thismeans. Further, the position of the heat dissipator 11 in the X-Ydirections is determined by causing the heat dissipator 11 to contacteach of the X-Y direction surfaces within the inner perimeter surface ofthe hole 2 e of the case 2.

The heat dissipator 11 radiates to the exterior of the magnetic sensordevice 100 the heat generated mainly by the magnetoresistance effectelement 4 and the signal amplification IC 5. The heat dissipator 11 hasa role of suppressing high temperature in the magnetic sensor device 100in itself.

The signal processing board 13 is electrically connected through thecable 3 c to the sensor board 3. The Z-direction position of the signalprocessing board 13 is determined by causing contact between oneZ-direction surface (surface of the side of the conveyance path of theobject to be detected 20) of the signal processing board 13 and theboard mounting surface 2 f of the case 2. Due to use of the fasteners 8to fix the signal processing board 13 in a state in which the axis ofthe board mounting hole 2 g of the case 2 and the axis of the boardmounting hole 13 a of the signal processing board 13 overlap, X-Ydirection position of the signal processing board 13 relative to thecase 2 is determined. Here, the fastener 8, for example, is a screw.However, this configuration is not limiting, and a component other thana screw may be used as the fastener 8, as long as the fastener 8 is ameans, such as caulking and the like, that enables fixing of the signalprocessing board 13 to the case 2.

The method of production of the magnetic sensor device of Embodiment 1of this disclosure is explained below using FIG. 3A to FIG. 4B and FIG.5 to FIG. 10. The production method of the magnetic sensor device 100includes a carrier assembly step, a sensor board assembly step, apermanent magnet assembly step, and a final assembly step. Among thesesteps, the carrier assembly step is performed prior to the sensor boardassembly step, and the final assembly step is performed after the othersteps.

The carrier assembly step is explained using FIGS. 3A and 3B. Thecarrier assembly step is a step of assembly of the metallic carrier 7 byfixing the magnetic carrier 7 a to the opening 7 d of the non-magneticcarrier 7 b. The magnetic carrier 7 a is fixed, for example, by adhesionusing a resin adhesive, bonding using caulking, and the like. Ifthicknesses are different between the magnetic carrier 7 a and thenon-magnetic carrier 7 b at this time, one of the Z-direction surfacesis taken to be a standard, and the other surface is arranged to form asingle surface free of a step.

The sensor board assembly step is explained using FIGS. 4A and 4B. Thesensor board assembly step is a step for attaching the sensor board 3and the like to one surface of the metallic carrier 7. In the sensorboard assembly step, the magnetoresistance effect elements 4 arearranged parallel to the X axis direction on the magnetic carrier 7 a,and the signal amplification ICs 5 are arranged parallel to the X axisdirection on the non-magnetic carrier 7 b portion, of the metalliccarrier 7. Then the magnetoresistance effect elements 4 and the signalamplification ICs 5 are electrically connected to the conductive member3 b of the sensor board 3 through the wires 6.

During attachment of the sensor board 3, the magnetoresistance effectelements 4, and the signal amplification ICs 5 to the metallic carrier7, the surface used for attachment to the metallic carrier (+Z sidesurface of the metallic carrier 7) is a surface that has no step betweenthe magnetic carrier 7 a and the non-magnetic carrier 7 b.

When the magnetoresistance effect elements 4 are attached to themagnetic carrier 7 a, the magnetoresistance effect elements 4 areattached so that the magnetoresistance effect elements 4 do not protrudein the +Z direction from the opening 3 e of the sensor board 3. In thesame manner, when the signal amplification ICs 5 are attached to thenon-magnetic carrier 7 b, the signal amplification ICs 5 are attached sothat the signal amplification ICs 5 do not protrude in the +Z directionfrom the openings 3 f of the sensor board 3.

The magnet assembly step is explained using FIG. 5. The magnet assemblystep is a step integrating together the magnet 9 and the yoke 10.Further, the magnet 9 is not necessarily a single component, and aplurality of magnets 9 separated from one another in the X direction(longitudinal direction) may be integrated together. The position of themagnet 9 relative to the yoke 10 is determined by attaching the magnets9 to a +Z side surface of the yoke 10, and aligning side surfaces ineach of the X and Y directions of the magnet 9 and yoke 10. At thistime, all the S pole and N pole directions of all the magnets 9 arealigned in the same direction. The magnets 9 are fixed to the yoke 10using an adhesive and the like.

The final assembly step is described using FIGS. 6 to 10. The finalassembly step has procedures such as those described below. The magnet 9is fixed to the metallic carrier 7 as illustrated in FIG. 6. Thismetallic carrier 7, with the affixed magnet 9, is fixed to the case 2 asillustrated in FIG. 7. Further, the heat dissipator 11 is fixed to theyoke 10 as illustrated in FIG. 8. Moreover, the cover 1 is fixed to thesensor board 3 as illustrated in FIG. 9. FIG. 10 illustrates themagnetic sensor device with the signal processing board 13 fixed to thecase 2 and with the signal processing board 13 electrically connected tothe sensor board 3.

As shown in FIG. 6, the surface (surface of the +Z side) of the magnet 9opposite to the surface of fixing of the yoke 10 is attached to thesurface (surface of the −Z side) of the metallic carrier 7 opposite tothe surface attached to the sensor board 3. At this time, the magnet 9is arranged along the magnetic carrier 7 a, and the X-direction centersof the magnet 9 and the magnetic carrier 7 a are aligned. Further,position of the magnet 9 affects the performance of the magnetic sensordevice, and thus a jig may be separately used for adjustment of thefixing position of the magnet 9.

As illustrated in FIG. 7, the surface (surface of the −Z side) of theside of the metallic carrier 7 opposite to the surface of attachment ofthe sensor board 3 is contacted against the step 2 a of the case 2. Bycausing the side surface of the metallic carrier 7 to contact the innersurface of the hole 2 b of the case 2, the metallic carrier 7 is fittedinto the hole 2 b from the opening thereof. By this means, the magnet 9is arranged within the hole 2 c of the case 2.

As illustrated in FIG. 8, the heat dissipator 11 is attached to thesurface (surface of the −Z side) of the side of the yoke 10 opposite tothe surface of attachment of the magnet 9. At this time, position of theheat dissipator 11 in the X-Y directions is determined by fitting theheat dissipator 11 into the hole 2 e of the case 2.

As illustrated in FIG. 9, the surface (surface of the −Z side) of theside of the cover 1 opposite to the conveyance surface 1 b is attachedto the surface (surface of the +Z side of the sensor board 3) of theside of the sensor board 3 opposing the surface contacting the metalliccarrier 7. At this time, the cover 1 is attached so as to partiallycover the +Y side and −Y side surfaces (surfaces parallel to the X-Zplane) of the case 2. Position of the cover 1 is determined in the Xdirection by aligning the X-direction center of the cover 1 with theX-direction center of the case 2.

As illustrated in FIG. 10, the signal processing board 13 is attached tothe case 2 from the −Z side, and the surface (one surface in the Zdirection) of the +Z side of the signal processing board 13 is made tocontact the board mounting surface 2 f of the case 2. Also, the boardmounting hole 13 a of the signal processing board 13 and the boardmounting hole 2 g of the case 2 are made to overlap, and the fastener 8is screwed into the board mounting hole 13 a and the board mounting hole2 g. The signal processing board 13 is positioned relative to the case 2by this means. Moreover, the cable 3 c is electrically connected to thesignal processing board 13.

Next, FIG. 1 is used to describe the path of heat transmitted from theinterior of the magnetic sensor device 100 to the exterior air.

The main sources of heat in the magnetic sensor device 100 are themagnetoresistance effect element 4 and the signal amplification IC 5.The heat generated by the magnetoresistance effect element 4 and thesignal amplification IC 5 is transmitted to the metallic carrier 7 thatcontacts the magnetoresistance effect element 4 and the signalamplification IC 5. The metallic carrier 7 contacts the sensor board 3,the case 2, and the magnet 9. The non-conductive member 3 a of thesensor board 3 is formed from glass epoxy and does not include metal forconduction. Thus the heat conduction coefficient of the non-conductivemember 3 a is relatively low (heat conduction coefficient of generalglass epoxy is 0.4 W/m·K). Further, due to formation of the case 2 fromresin, the heat conduction coefficient of the case 2 is relatively low(heat conduction coefficient of general polycarbonate resin is 0.24W/m·K). On the other hand, the magnet 9 is formed as a neodymiumsintered magnet (heat conduction coefficient of general neodymiumsintered magnet is 6.5 W/m·K), and the heat conduction coefficient ofthe magnet 9 is higher than the heat conduction coefficients of themetallic carrier 7 and the case 2. Thus most of the heat from themetallic carrier 7 is transmitted to the magnet 9 (heat conductioncoefficient of general neodymium sintered magnet is 6.5 W/m·K).

The magnet 9 contacts the metallic carrier 7. The metallic carrier 7contacts the yoke 10, to which is attached the heat dissipator 11. Thusthe heat transmitted to the magnet 9 is transmitted to the metalliccarrier 7 and the yoke 10, and is radiated from the heat dissipator 11.

As described above, in the magnetic sensor device 100 of the presentEmbodiment 1, the heat dissipator 11 is arranged in close contact withthe −Z side (side opposite to the conveyance path) of the magneticcircuit 30. Thus temperature rise of the magnetic sensor device 100 issuppressed, which enables the suppression of demagnetization of themagnet 9 by heat, and enables the obtaining of stable output withoutlowering of sensitivity.

For example, in the case of a magnetic sensor device 200, as illustratedin the comparative example of FIG. 11, that has no heat dissipator 11and in which the opening of the hole 2 e is not formed in the case 2,the heat generated by the magnetoresistance effect elements 4 and thesignal amplification ICs 5 are transmitted from the magnetoresistanceeffect elements 4 and the signal amplification ICs 5, in order, to themetallic carrier 7, magnet 9, and yoke 10. Then heat from the yoke 10 isunable to be transmitted to the exterior of the magnetic sensor device200 except by thermal radiation. Moreover, even though heat istransmitted to the case 2 by thermal radiation, due to formation of thecase 2 from resin, heat radiation efficiency is low.

Thus transmission of the heat generated by the magnetoresistance effectelement 4 and the signal amplification IC 5 to the exterior air tends tobe difficult, and the temperature of the magnetic sensor device 200tends to be high. When the temperature of the magnet 9 becomes high, themagnetism field applied to the object to be detected becomes weak, andperformance of the magnetic sensor device 200 declines due todemagnetization.

In contrast, the heat dissipator 11 is arranged in close contact withthe magnetic circuit 30 in the magnetic sensor device 100 of the presentEmbodiment 1, and thus rise of temperature of the magnetic sensor device100 is suppressed, the demagnetization of the magnet 9 due to heat canbe suppressed, and stable output is obtained without lowering ofsensitivity.

Further, the case 2 of the magnetic sensor device 100 is formed fromresin. However, this configuration is not limiting. The case 2 may beformed from a material that has a high heat transfer coefficient, suchas a metal and the like. Such configuration enables radiation of heatthrough the case 2 to the exterior air, thereby enabling furtherincrease of heat dissipation efficiency.

Embodiment 2

In Embodiment 1 of the present disclosure, the magnetic sensor device isdescribed in which the heat dissipator 11 closely contacts the surfaceof the magnetic circuit 30 of the side opposite to the surface of theconveyance path side. In Embodiment 2, a magnetic sensor device isdescribed in which the heat dissipator 11 closely contacts a surface ofthe magnetic circuit 30 other than surface of the side opposite to thesurface of the conveyance path side.

FIG. 12 is used for description of the configuration of the magneticsensor device of Embodiment 2 of the present disclosure. FIG. 12 is across-sectional drawing of a magnetic sensor device 100A. In FIG. 12,constituent elements that are the same or equivalent to those of FIG. 1are assigned the same reference signs.

As illustrated in FIG. 12, the heat dissipator 11 of the magnetic sensordevice 100A is exposed to the exterior. Further, in order to determinethe position of the heat dissipator 11, the hole 2 e is formed in thecase 2 of the magnetic sensor device 100A. The opening of the hole 2 eis formed in a −Y direction side surface of the case 2. X-Z directionpositions of the heat dissipator 11 are determined by fitting the heatdissipator 11 into the case 2 from the hole 2 e opening. Further,position of the heat dissipator 11 in the Y-axis direction is determinedby attachment of the heat dissipator 11 to the −Y side surface of theyoke 10 and the magnet 9 constituting the magnetic circuit 30.

That is to say, the heat dissipator 11 closely contacts the Y-directionside surface of the magnetic circuit 30, which is the surface of themagnetic circuit 30 other than the conveyance path-side surface of themagnetic circuit 30.

As described above, in the present Embodiment 2, the heat generated bythe magnetoresistance effect element 4 and the signal amplification IC 5is transmitted, in order, to the metallic carrier 7 and the magnet 9,and is radiated to the exterior from the magnet 9 through the heatdissipator 11. Due to radiation of the heat to the exterior withouttraversing the yoke 10, thermal resistance up until radiation to theexterior can be made small, and the efficiency of thermal radiation canbe improved. Moreover, in contrast to the magnetic sensor device 100 ofthe present Embodiment 1, the heat dissipator 11 is exposed to theexterior, and thus the release of heat to the exterior is not impeded bythe signal processing board 13. Thus the present Embodiment 2 enablesfurther improvement of the heat dissipation efficiency.

In the magnetic sensor is described in Embodiment 2, the heat dissipator11 is in close contact with the Y-direction side surface of the magneticcircuit 30. A configuration may be used in which the heat dissipator 11is in close contact with both the Y-direction side surface of themagnetic circuit 30 and the surface of the magnetic circuit 30 of theside opposite to the surface of the conveyance direction side.

Embodiment 3

Configuration of a magnetic sensor device of Embodiment 3 of the presentdisclosure is described next using FIGS. 13A, 13B and 14. FIG. 13A is aperspective view of a cross-sectioned portion of the case 2 of themagnetic sensor device. The FIG. 13B is a cross-sectional drawing of thecase 2 of the magnetic sensor device. FIG. 14 is a cross-sectionaldrawing of the magnetic sensor device. In FIGS. 13A, 13B and 14,constituent elements that are the same or equivalent to those of FIG. 1are assigned the same reference signs.

As illustrated in FIGS. 13A, 13B and 14, the heat dissipator 11 of themagnetic sensor device 100B is insert-molded in the case 2. The heatdissipator 11 has a plurality of fins 11 b projecting toward the side(−Z side) opposite to the conveyance path side. The plurality of fins 11b, for example, is arranged in the Y direction. The heat dissipator 11is held by the case 2 by embedding of both end portions of the +Y sideand −Y side of the heat dissipator 11 in the case 2.

As described above, the heat dissipator 11 in the present Embodiment 3is insert-molded in the case 2. Thus the number of components of themagnetic sensor device 100B decreases. Further, the operation ofattaching the heat dissipator 11 to the yoke 10 during the finalassembly step becomes unnecessary.

Moreover, due to formation of the heat dissipator 11 from a metal, whichgenerally has a high heat transfer coefficient, toughness of the case 2can be increased by insert-molding of the heat dissipator 11 in the case2. Further, in Embodiment 3, the heat dissipator 11 is insert-molded inthe case 2. However, this configuration is not limiting. The heatdissipator 11 may be integrally formed with the case 2 by a method otherthan insert-molding.

Embodiment 4

Configuration of a magnetic sensor device of Embodiment 4 of the presentdisclosure is described next using FIGS. 15 and 16. FIG. 15 is aperspective view of the magnetic sensor device of Embodiment 4 with theboard mounting surface of the case oriented upward. FIG. 16 is across-sectional drawing of the magnetic sensor device of Embodiment 4.In FIGS. 15 and 16, constituent elements that are the same or equivalentto those of FIG. 1 are assigned the same reference signs.

In the surface of the −Z side of the case 2 of the magnetic sensordevice 100C illustrated in FIG. 15, in addition to the board mountingsurface 2 f, an offset surface 2 h is formed that is offset in the +Zdirection from the board mounting surface 2 f. As illustrated in FIG.16, space in the vicinity of the heat dissipator 11 communicates withthe exterior due to formation of the offset surface 2 h. This has theeffect of enabling improvement of heat radiation efficiency.

Embodiment 5

Configuration of a magnetic sensor device of Embodiment 5 of the presentdisclosure is described next using FIGS. 17 and 18. FIG. 17 is aperspective view of the heat dissipator of the magnetic sensor device ofEmbodiment 5. FIG. 18 is a cross-sectional drawing of the magneticsensor device of Embodiment 5. In FIGS. 17 and 18, constituent elementsthat are the same or equivalent to those of FIG. 1 are assigned the samereference signs.

As illustrated in FIGS. 17 and 18, in the present Embodiment 5, the heatdissipator 11 of the magnetic sensor device 100D has a plate-shaped base11 c having fins 11 b formed on the surface of the −Z side, and a pairof projections 11 a (sidewalls) for determining the Y-directionpositions of the magnet 9 and the yoke 10. The projections 11 a arearranged projecting in the +Z direction from both Y-direction endportions of the base 11 c of the heat dissipator 11.

As described above, in the present Embodiment 5, the heat dissipator 11has the projections 11 a. Thus the jig, which is necessary in thepermanent magnet assembly step of the magnetic sensor device 100 ofEmbodiment 1 for fixing the magnet 9 and the yoke 10, can becomeunnecessary. Further, insertion of the magnet 9 and the yoke 10 betweenthe projections 11 a enables omission of the step in which the heatdissipator 11 is attached to the magnet 9 and the yoke 10. Moreover,contact surface area between the magnet 9 and the heat dissipator 11increases due to contact of the +Y side and −Y side surfaces of themagnet 9 with the projections 11 a. Heat radiation efficiency can beincreased by this configuration.

Embodiment 6

Configuration of a magnetic sensor device of Embodiment 6 of the presentdisclosure is described next using FIGS. 19 and 20. FIG. 19 is aperspective view of the heat dissipator of the magnetic sensor device ofEmbodiment 6. FIG. 20 is a cross-sectional drawing of the magneticsensor device of Embodiment 6. In FIGS. 19 and 20, constituent elementsthat are the same or equivalent to those of FIG. 1 are assigned the samereference signs.

In Embodiment 6, the heat dissipator 11 is formed as a C-shaped channelthat has: a plate-shaped base 11 c for formation of fins 11 b on the −Zside surface, and two of the fins 11 b formed extending from the +Y sideand −Y side end portions of the base 11 c.

As described above, the heat dissipator 11 of the present Embodiment 6has two fins 11 b. Thus the shape of the heat dissipator 11 can besimplified, and fabrication cost of the heat dissipator 11 can bedecreased.

The heat dissipator 11 of the magnetic sensor device 100 illustrated inEmbodiment 1 generally is molded by extrusion molding due to the largenumber of fins 11 b. In contrast, the present Embodiment 6 enablesproduction by bending of sheet material and enables selection of asuitable production method. Moreover, setting the dimensions of theC-shaped channel to those of a standard product enables decrease of thefabrication cost.

Embodiment 7

Configuration of a magnetic sensor device of Embodiment 7 of the presentdisclosure is described next using FIG. 21. FIG. 21 is a cross-sectionaldrawing of the magnetic sensor device of Embodiment 7. The magneticsensor device 100F enables detection only in the case in which theobject to be detected 20 is magnetic. In FIG. 21, constituent elementsthat are the same or equivalent to those of FIG. 1 are assigned the samereference signs.

As illustrated in FIG. 21, in contrast to the metallic carrier 7 of themagnetic sensor device 100 of the present Embodiment 1, the metalliccarrier 7 of the magnetic sensor device 100F is configured from a singlesheet of non-magnetic plate. The magnetic carrier 7 a has a role ofarranging the direction of the magnetic field of the magnet 9 in the Zdirection. However, in the case in which the object to be detected 20 ismagnetized, the magnetic carrier 7 a may be omitted from the metalliccarrier 7. Heat dissipation efficiency can be improved due to themetallic carrier 7 in Embodiment 7 of the present disclosure not havingthe magnetic carrier 7 a.

For example, in Embodiment 1 of the present disclosure and Embodiment 7of the present disclosure, the magnetic carrier 7 a is formed from iron(general heat transfer coefficient is 84 W/m·K), and the non-magneticcarrier 7 b is formed from copper (general heat transfer coefficient is398 W/m·K). Thus in Embodiment 7 of the present disclosure, heatdissipation efficiency can be increased due to formation of the metalliccarrier 7 from only the non-magnetic carrier 7 b, which has a high heattransfer coefficient.

The foregoing describes some example embodiments for explanatorypurposes. Although the foregoing discussion has presented specificembodiments, persons skilled in the art will recognize that changes maybe made in form and detail without departing from the broader spirit andscope of the invention. Accordingly, the specification and drawings areto be regarded in an illustrative rather than a restrictive sense. Thisdetailed description, therefore, is not to be taken in a limiting sense,and the scope of the invention is defined only by the included claims,along with the full range of equivalents to which such claims areentitled.

This application claims the benefit of Japanese Patent Application No.2014-125159 including the specification, the claims, the figures and theabstract, filed on Jun. 18, 2014. The entire specification, claims, anddrawings of Japanese Patent Application No. 2014-125159 are incorporatedby reference herein.

REFERENCE SIGNS LIST

-   -   1 Cover    -   1 a Taper    -   1 b Conveyance surface    -   2 Case (housing)    -   2 a Step    -   2 b, 2 c, 2 e Hole    -   2 f Board mounting surface    -   2 g Board mounting hole    -   2 h Offset surface    -   3 Sensor board    -   3 a Non-conductive member    -   3 b Conductive member    -   3 c Cable    -   3 d Positioning hole    -   3 e, 3 f Opening    -   4 Magnetoresistance effect element    -   5 Signal amplification IC (signal processor)    -   6 Wire    -   7 Metallic carrier    -   7 a Magnetic carrier (magnetic body)    -   7 b Non-magnetic carrier (non-magnetic body)    -   7 c Positioning hole    -   7 d Opening    -   8 Fastener    -   9 Magnet    -   10 Yoke    -   11 Heat dissipator    -   11 a Projection (sidewall)    -   11 b Fin    -   13 Signal processing board    -   13 a Board mounting hole    -   20 Object to be detected    -   21 Conveyance direction    -   30 Magnetic circuit    -   100, 100A, 100B, 100C, 100D, 100E, 100F, 200 Magnetic sensor        device

1: A magnetic sensor device comprising: a magnetic circuit forming amagnetic field; a magnetoresistance effect element, mounted on a surfaceof a conveyance path side of an object to be detected of the magneticcircuit, and configured to output a change of the magnetic field as achange of a resistance value; and a heat dissipator disposed in closecontact with a surface of the magnetic circuit other than the surface ofthe conveyance path side of the magnetic circuit; wherein the magneticcircuit comprises: a magnet, a metallic carrier, having one surface inclose contact with the surface of the conveyance path side of themagnet, and carrying the magnetoresistance effect element on anothersurface, and a yoke having one surface closely contacting a surface ofthe magnet of a side opposite to the conveyance path side, and havinganother surface closely contacting the heat dissipator, and the heatdissipator is disposed in close contact with the surface of the magneticcircuit of a side opposite to the conveyance path side of the magneticcircuit, and comprises a pair of sidewalls, extending in a directionparallel to the surface of the conveyance path side of the heatdissipator, and extending in a direction perpendicular to a conveyancedirection of the object to be detected, and the yoke and the magnet aredisposed between the pair of sidewalls. 2-3. (canceled) 4: A magneticsensor device comprising: a magnetic circuit forming a magnetic field; amagnetoresistance effect element, mounted on a surface of a conveyancepath side of an object to be detected of the magnetic circuit, andconfigured to output a change of the magnetic field as a change of aresistance value; and a heat dissipator disposed in close contact with asurface of the magnetic circuit other than the surface of the conveyancepath side of the magnetic circuit; wherein the heat dissipator isdisposed in close contact with the surface of the magnetic circuit of aside opposite to the conveyance path side of the magnetic circuit, themagnetic circuit comprises, a magnet, a metallic carrier, having onesurface in close contact with the surface of the conveyance path side ofthe magnet, and carrying the magnetoresistance effect element on anothersurface, and a yoke having one surface closely contacting a surface ofthe magnet opposite to the conveyance path side, and having anothersurface closely contacting the heat dissipator, the metallic carriercomprises: a magnetic body upon which is disposed the magnetoresistanceeffect element; and a non-magnetic body bonded to the magnetic body andto carry a signal processor electrically connected to themagnetoresistance effect element. 5-6. (canceled) 7: The magnetic sensordevice according to claim 4, wherein the heat dissipator comprises: abase that is plate-like; and a pair of fins extending from bothconveyance-direction ends of the base. 8: The magnetic sensor deviceaccording to claim 1, wherein the magnetic sensor device furthercomprises a housing in which a hole is formed that penetrates in adirection orthogonal to the surface of the conveyance path side of thehousing and orthogonal to the conveyance direction; and the holecontains the magnetic circuit, the magnetoresistance effect element, andthe heat dissipator. 9: The magnetic sensor device according to claim 8,wherein in a surface of the housing opposite to the conveyance path sideare formed: a board mounting surface for mounting of a board; and anoffset surface offset from the board mounting surface toward theconveyance path side. 10: The magnetic sensor device according to claim8, wherein the heat dissipator contacts an inner circumferential surfaceof the hole. 11: The magnetic sensor device according to claim 8,wherein the heat dissipator is insert-molded in the housing. 12-16.(canceled) 17: The magnetic sensor device according to claim 4, whereinthe magnetic sensor device further comprises a housing in which a holeis formed that penetrates in a direction orthogonal to the surface ofthe conveyance path side of the housing and orthogonal to a conveyancedirection; and the hole contains the magnetic circuit, themagnetoresistance effect element, and the heat dissipator. 18: Themagnetic sensor device according to claim 17, wherein in a surface ofthe housing opposite to the conveyance path side are formed: a boardmounting surface for mounting of a board; and an offset surface offsetfrom the board mounting surface toward the conveyance path side. 19: Themagnetic sensor device according to claim 17, wherein the heatdissipator contacts an inner circumferential surface of the hole. 20:The magnetic sensor device according to claim 17, wherein the heatdissipator is insert-molded in the housing. 21: A magnetic sensor devicecomprising: a magnetic circuit forming a magnetic field; amagnetoresistance effect element, mounted on a surface of a conveyancepath side of an object to be detected of the magnetic circuit, andconfigured to output a change of the magnetic field as a change of aresistance value; a heat dissipator disposed in close contact with asurface of the magnetic circuit other than the surface of the conveyancepath side of the magnetic circuit; and a housing in which a hole isformed that penetrates in a direction orthogonal to the surface of theconveyance path side of the housing and orthogonal to a conveyancedirection, the hole contains the magnetic circuit, the magnetoresistanceeffect element, and the heat dissipator, and the heat dissipator isinsert-molded in the housing. 22: A magnetic sensor device comprising: amagnetic circuit forming a magnetic field; a magnetoresistance effectelement, mounted on a surface of a conveyance path side of an object tobe detected of the magnetic circuit, and configured to output a changeof the magnetic field as a change of a resistance value; a heatdissipator disposed in close contact with a surface of the magneticcircuit other than the surface of the conveyance path side of themagnetic circuit; and a housing in which a hole is formed thatpenetrates in a direction orthogonal to the surface of the conveyancepath side of the housing and orthogonal to a conveyance direction,wherein the hole contains the magnetic circuit, the magnetoresistanceeffect element, and the heat dissipator, and in a surface of the housingopposite to the conveyance path side are formed: a board mountingsurface for mounting of a board; and an offset surface offset from theboard mounting surface toward the conveyance path side.